ios – 升级到Swfit 3：无法覆盖已标记为不可用的’init’

class MyClass: ParentWithUnavailableInitializer {
    init(workaround _: Void = ()) {
        // Call a designated initializer
        super.init(param: "a very sensible value")
    }
}

// At a call site
let obj = MyClass()

适用于Swift 3.2和Swift 4.